Prof. Mark Rudner – University of Washington

Title: “The Lindblad Quantum Master Equation: Not Just for quantum Optics Anymore”

Abstract: With the exception of the universe as a whole, the evolution of a quantum system is generically non-unitary due to the coupling between the system and its environment. In quantum optics, the powerful framework of Lindblad master equations has been developed and employed for many years to describe the effective evolution of atomic-like systems in the presence of electromagnetic and other environmental degrees of freedom. Importantly, explicit derivations of Lindblad master equations have traditionally relied on highly restrictive assumptions on energy level spacings that limit its applicability to few-level/few-body systems. In this talk I will review the basic features of evolution of open quantum systems, and describe a new route to obtaining the Lindblad equation which circumvents all restrictive assumptions on the nature of the system at hand. This “universal Lindblad equation” can therefore be applied to a wide range of many-body systems, including emerging quantum hardware with several to many coupled qubits and many-body systems driven far from equilibrium. The explicit expressions for the “jump operators” that describe incoherent processes induced by the bath have a natural interpretation in terms of an operator spreading picture, akin to that which has recently provided much insight into thermalization of closed quantum systems. I will conclude with a discussion of future prospects and applications of this new framework.

Bio: Mark Rudner is the Kenneth K. Young Memorial Professor of Physics at the University of Washington. His research interests span a broad range of topics in theoretical condensed matter physics and quantum dynamics. Following his PhD at MIT, in which he studied classical and quantum control in solid state spin and superconducting qubits, as well as transport in graphene, in 2008 Mark moved to Harvard for a postdoctoral fellowship. During this time, he developed foundational works on topological phenomena in both driven (“Floquet”) and open (non-Hermitian) quantum systems. In 2012, Mark moved to Copenhagen, where he joined the Center for Quantum Devices at the Niels Bohr Institute and took charge of the Condensed Matter Theory group at the Niels Bohr International Academy. Over the next decade, Mark maintained a role as one of the leaders in the emerging fields of Floquet engineering and non-equilibrium quantum dynamics, while further exploring novel (linear and non-linear) collective phenomena that arise from the interplay of quantum geometry and interparticle interactions. In 2021 Mark joined the University of Washington, where he is continuing these efforts while expanding into new directions in collaboration with his experimental and theoretical colleagues.